1. Field of the Invention
The present invention relates to multi-part connecting devices and, more particularly to improved detent mechanisms for resisting unwanted rotation in electrical connectors having a plug housing with a coupling ring.
2. Description of Related Art
In most situations, electrical connector assemblies are adequately held together by friction in the threaded components and the mating surfaces. However, in vehicle, aircraft and spacecraft applications, the connector assemblies are oftentimes subjected to severe vibrational forces. Such forces, over time, loosen the connections which may produce serious problems in operating the vehicle or craft.
To overcome the above problems, literally hundreds of devices have been developed to affirmatively secure together the electrical connector parts. For example, keys, pins and locks have oftentimes been used. But, the connection of such devices may have an adverse impact on the structural integrity and use of the assembly. Also, they are not suitable for use when the connectors are situated in inaccessible locations.
The use of resins, solders and mechanical locking rings are usually effective if it is desired to permanently lock the assembly together. However, most often it is preferred to be able to disconnect the assemblies for replacement or testing purposes.
Accordingly, a variety of devices have evolved that resist decoupling, but do not permanently prevent it. U.S. Pat. No. 4,407,529 describes a plurality of spring-loaded balls radially mounted in a coupling nut. The balls releasably engage spaced-apart depressions in the outer circumference of a plug housing. Spring tension creates resistance from dislodgement of the balls from the depressions which, thereby, inhibits unwanted rotation of the coupling nut.
A problem with the above arrangement is the balls and depressions must be engaged, i.e., aligned, to resist decoupling. However, this is difficult to achieve when constructing and assembling the connector parts. Additionally, maintenance costs are extremely high for such intricate devices.
Both U.S. Pat. Nos. 4,793,821 and 4,834,667 utilize a radially outwardly extending spring means for engaging teeth formed on the inside of a collar. Again, the difficulty and expense in forming a row of teeth about the interior periphery of a multiribbed collar, creates a very significant manufacturing disadvantage. Difficulties further arise in properly maintaining the spring positions, as they extend from flattened grooves on a sleeve, during placement of the sleeve within the collar.
In U.S. Pat. No. 4,359,254, a plastic coupling ring is placed adjacent a connector housing having an inner lip from which extend a series of ramps. The ring itself is provided with a plurality of deflectable fingers which slide over the ramps in one direction. However, when moved in an opposite direction, the fingers have difficulty in riding over the blunt ends of the ramps. This creates the desired anti-rotation resistance. Unfortunately, it also causes excessive wear and reduces the service life of the device.
Additionally, another significant disadvantage of the above device is the high cost and difficulty in molding undercut finger shapes about the interior surfaces of the coupling ring. Still further, if the fingers break or weaken, the entire ring will have to be replaced.
An improvement over the above system is shown in U.S. Pat. No. 4,542,95. This arrangement utilizes individual spring members, rather than fingers, which are integral with the coupling ring. The spring members are separately riveted to the inside of the ring to flexibly engage bayonet pins extending radially from the outer surface of a connector shell. The pins readily slide over the springs during rotational engagement of the coupling to the shell. However, greater resistance occurs when the coupling is rotated in the opposite direction.
A significant problem with the above system is its limited application. That is, electrical connections are not always made to a receptacle shell. In-line connections are common and it would be far more versatile to simply provide anti-decoupling means between the coupling part and its associated plug housing. Also, it is difficult and labor intensive to position and secure the bayonet pins in an external receptacle shell in precise coordination with springs on a coupling ring when the ring is part of a separate independent connector assembly.